Waveguide systems in lighting, especially in LCD backlighting, are known in the art.
GB 2430071 for instance has for its object to provide a backlight unit having good display quality, and a liquid crystal display device provided with the same. To this end, a light source, a reflection sheet, a light guide plate, a gas space, and a diffusion plate are installed. The reflection sheet, light guide plate, gas space, and a diffusion plate are superposed in the order mentioned. The light source is in the form of individual light sources having different spectra or different amounts of luminescence and being disposed in the vicinity of the incident surface of the light guide plate. The surface of the light guide plate opposite to the reflecting sheet is provided with scattering dots, whereby the light transmitted through the light guide plate is taken out to the reflection plate side.
US 2004183962 describes a backlight module for providing light with a more uniform light distribution and greater brightness. The backlight module includes at least a luminary for providing light, a light guide assembly disposed adjacent to the luminary for guiding a first portion of the light, a translucent membrane having a plurality of openings, and a reflector disposed below the light guide assembly. A second portion of the light passes upwardly through the openings and a third portion of the light is directed upwardly by the light guide assembly after being reflected by the translucent membrane and the reflector. The light guide assembly includes a plurality of light guide plates, wherein the bottom of at least one light guide plate can be a triangular concave or an arc concave, and the light guide plates can contain some doping particles.
Further, US 2006055843 describes an LCD backlight apparatus which includes a light guide plate placed under an LCD panel of the LCD to guide light to the LCD panel. The light guide plate has an even upper surface and a scattering pattern formed in a bottom surface. A plurality of monochromatic light sources are placed in line at a side of the light guide plate to radiate light along the plane direction of the light guide plate between the upper and bottom surfaces of the light guide plate. The light sources are adapted to radiate light beams at a predetermined beam angle so that the light beams reach the scattering pattern only after having propagated a predetermined reference distance necessary for forming white light when mixed together. The LCD backlight apparatus can reduce the bezel width without increasing the thickness of an LCD.